MILWAUKEE — After the Celtics’ 106-100 home loss to the 76ers on Friday, Celtics coach Doc Rivers became irritated about questions regarding the starting lineup.

He stressed that the starting lineup is irrelevant, the key is minutes played. But after having seen more unspectacular efforts from Courtney Lee and Jared Sullinger, Rivers decided to make changes to the lineup against the Bucks, inserting Jason Terry and Brandon Bass, both of whom had provided sparks off the bench.

Sullinger started the previous three games and scored 4 points in each in roughly 24 minutes per game. Lee scored 11 points in 24 minutes in the 120-107 season-opening loss to the Miami Heat but hasn’t reach double figures since. He scored 2 points in Wednesday’s win over Washington and 4 on Friday.

Against the Bucks, Sullinger barely saw the floor (2 points, 4 rebounds, 7 minutes), while Lee had no points (0 for 3 from the field) in 28 minutes.

“It has nothing to do with the starting lineup — I am looking for a team that can play 48 minutes,” Rivers said. “And we’ve yet to find that, so that’s what we’re going to keep searching for. When you think about our games, we have started out pretty well. It’s when we sub out, what we feel like, obviously we take a drop and it’s as much offense as defense.”

Terry was fourth on the team in scoring going into the Bucks game, averaging 11 points in about 25 minutes per game. He has been a sixth man most of his career but said he was open to starting. Bass, meanwhile, started most of last season and the first two games this year before giving way to Sullinger, but he has been more aggressive offensively and stayed out of foul trouble.

Sullinger, on the other hand, has played 100 minutes this season and been whistled for 12 personal fouls, second on the team to Paul Pierce.

“We feel like we need more scoring to stay on the floor when Kevin goes out,” Rivers said. “Hey listen, we’ll see. I’ll let you know how it goes. I’m just searching for the right group, not only the right mix, the right group.

“I was really disappointed in our transition [defense against the 76ers]. We gave up 38 points in transition offense. We’ll never win that way. We can’t win that way.”

Not his best shot

Perhaps the biggest surprise so far is the struggles of Lee, who came to Boston with the reputation as an above-average outside shooter and consistent scorer.

After his 0-fer against the Bucks, Lee is averaging 5 points per game, having attempted only 31 shots in 151 minutes. By comparison, Pierce has attempted 94 shots.

Lee said he has been working feverishly on his jumper to try to snap out of his slump, understanding the high expectations in Boston.

“I’m not shooting the ball like I’m usually capable of shooting,” he said. “That’s all.

“Being on this team, that’s something that I have to do. It will open up a lot for [Rajon] Rondo as far as driving. It will open up a lot for Pierce as far as driving and also KG.

“A lot of times when they get the ball, it’s a double-team coming from somewhere, so what you want to do is make teams pay for that double-team. It’s something I have to continue to work on until I get it to where it feels good.”